This invention relates to a pressure limiter-regulator using a single resilient means as a reaction member for both the pressure regulating action and the pressure limiting action.
A number of devices are known which make it possible to control and limit the pressure value of a hydraulic circuit to a preset value.
Other devices are also known which make it possible to control the pressure of a hydraulic circuit and to regulate that pressure to a desired value.
These two distinct devices are separated in the hydraulic circuit in which they are used and they are connected to each other by ducts.
Each of these devices comprises its own resilient means as a reaction member. In the devices which limit the pressure to a predetermined value, a ball is generally pushed by a resilient means against a seat, in the center of which there is a duct. When the pressure in the duct exceeds the predetermined value above which the hydraulic circuit might be damaged, the ball pushes the resilient means back and lets the oil pass into a chamber, which oil then leaves through another duct going out of the chamber and generally connected to the hydraulic circuit tank. In the pressure regulating devices, a central spindle can generally be moved to one side under the action of the hydraulic circuit pressure and to the opposite side under the action of a resilient means. Thus, the spindle is continuously balanced under these two opposed actions. This central spindle has several shoulders which, when moved sideways, act as a spool by closing or opening ports. The spool thus more or less throttles the inlet of the pressure oil and allows it to pass into the outlet duct.
These two types of devices also make use of two bodies, each with its own resilient means. If the hydraulic circuit is an integral part of a hydraulic block, each device requires its own bore and its own housing for its own resilient means.
It is an object of this invention to provide a single pressure limiter-regulator of a specially simple farbrication.